Infiniti Q45 (FY33). Manual - part 454

SGI974

Measuring voltage drop — Step by step

The step by step method is most useful for isolating excessive drops in low voltage systems (such as those
in “Computer Controlled Systems”).
Circuits in the “Computer Controlled System” operate on very low amperage.
The (Computer Controlled) system operations can be adversely affected by any variation in resistance in the
system. Such resistance variation may be caused by poor connection, improper installation, improper wire
gauge or corrosion.
The step by step voltage drop test can identify a component or wire with too much resistance.

SGI854

IDX

HOW TO PERFORM EFFICIENT DIAGNOSIS FOR AN ELECTRICAL INCIDENT

Circuit Inspection (Cont’d)

GI-31

CONTROL UNIT CIRCUIT TEST

System Description: When the switch is ON, the control unit lights up the lamp.

AGI059

HOW TO PERFORM EFFICIENT DIAGNOSIS FOR AN ELECTRICAL INCIDENT

Circuit Inspection (Cont’d)

GI-32

NOTICE

The flow chart indicates work procedures required to diagnose
problems effectively. Observe the following instructions before
diagnosing.
1)

Use the flow chart after locating probable causes of a
problem following the “Preliminary Check”, the “Symptom
Chart” or the “Work Flow”.

After repairs, re-check that the problem has been com-
pletely eliminated.

Refer to Component Parts and Harness Connector Loca-
tion for the Systems described in each section for
identification/location of components and harness con-
nectors.

Refer to the Circuit Diagram for Quick Pinpoint Check.
If you must check circuit continuity between harness con-
nectors in more detail, such as when a sub-harness is
used, refer to Wiring Diagram in each individual section
and Harness Layout in EL section for identification of har-
ness connectors.

When checking circuit continuity, ignition switch should
be “OFF”.

Before checking voltage at connectors, check battery volt-
age.

After accomplishing the Diagnostic Procedures and Elec-
trical Components Inspection, make sure that all harness
connectors are reconnected as they were.

Example

SGI101A

IDX

HOW TO FOLLOW FLOW CHART IN TROUBLE DIAGNOSES

GI-33

How to Follow This Flow Chart

Work and diagnostic procedure

Start to diagnose a problem using procedures indicated in
enclosed blocks, as shown in the following example.

CHECK POWER SUPPLY.
1. Stop engine.
2. Disconnect IACV-FICD solenoid

valve harness connector.

3. Start engine, then turn air condi-

tioner switch and blower fan
“ON”.

4. Check voltage between terminal

and ground with CONSULT-II

or tester.
Voltage: Battery voltage

Check item being performed.

Procedure, steps or
measurement results

Measurement results

Required results are indicated in bold type in the correspond-
ing block, as shown below:
These have the following meanings:

Battery voltage

→

11 - 14V or approximately 12V

Voltage: Approximately 0V

→

Less than 1V

Resistance: Continuity should exist

→

Approximately

Ω

Cross reference of work symbols in the text and
illustrations

Illustrations are provided as visual aids for work procedures.
For example, symbol

indicated in the left upper portion of

each illustration corresponds with the symbol in the flow chart
for easy identification. More precisely, the procedure under the
“CHECK POWER SUPPLY” outlined previously is indicated by
illustration

Symbols used in illustrations

Symbols included in illustrations refer to measurements or pro-
cedures. Before diagnosing a problem, familiarize yourself with
each symbol.

For symbols, refer to “CONNECTOR SYMBOLS”, (GI-14)
and “Key to symbols signifying measurements or proce-
dures” (GI-35).

DIRECTION MARK

Refer to “CONNECTOR SYMBOLS” on GI-14.

HOW TO FOLLOW FLOW CHART IN TROUBLE DIAGNOSES

GI-34

Content .. 452 453 454 455 ..